M8-R08: add atomic meter close and binding transfer

tests/test_meters.py

@@ -25,7 +25,10 @@ from sqlalchemy import create_engine, event as sa_event
 from sqlalchemy.orm import Session
 
 from app.models.energy import Meter
+from app.models.meter_source import MeterSource, MeterSourceBinding, MeterSourceChannel
 from app.services.meters import (
+    _as_utc,
+    close_meter,
     MeterIntervalError,
     MeterOverlapError,
     declare_meter,
@@ -35,6 +38,62 @@ from app.services.meters import (
 )
 
 
+def test_declare_and_close_reject_future_boundaries(session: Session):
+    future = datetime.now(UTC) + timedelta(minutes=5)
+    with pytest.raises(MeterIntervalError, match="future"):
+        declare_meter(session, label="future", started_at=future, reason="initial")
+    meter = _make_meter(session, started_at=datetime.now(UTC) - timedelta(hours=1))
+    with pytest.raises(MeterIntervalError, match="future"):
+        close_meter(session, meter, ended_at=future)
+    assert meter.ended_at is None
+
+
+def test_close_and_declare_reject_boundary_before_retained_closed_binding(session: Session):
+    """Lifecycle writes must not silently shorten immutable binding history."""
+    start = datetime.now(UTC) - timedelta(hours=3)
+    proposed_end = start + timedelta(hours=1)
+    meter = _make_meter(session, started_at=start)
+    binding = _make_binding(session, meter, started_at=start, ended_at=start + timedelta(hours=2))
+
+    with pytest.raises(MeterIntervalError, match="Closed binding extends"):
+        close_meter(session, meter, ended_at=proposed_end)
+    assert meter.ended_at is None
+    assert binding.ended_at == start + timedelta(hours=2)
+
+    with pytest.raises(MeterIntervalError, match="Closed binding extends"):
+        declare_meter(session, label="replacement", started_at=proposed_end, reason="meter_swap")
+    assert meter.ended_at is None
+    assert session.query(Meter).count() == 1
+
+
+def test_update_rejects_future_started_at_before_mutating_other_fields(session: Session):
+    """A future correction must not leak label/note changes into the Session."""
+    meter = _make_meter(
+        session,
+        started_at=datetime.now(UTC) - timedelta(hours=1),
+        label="Original",
+        note="Original note",
+    )
+    session.commit()
+    meter_id = meter.id
+
+    with pytest.raises(MeterIntervalError, match="future"):
+        update_meter(
+            session,
+            meter,
+            label="Changed",
+            note="Changed note",
+            started_at=datetime.now(UTC) + timedelta(minutes=5),
+        )
+    session.rollback()
+
+    with Session(session.bind) as observer:
+        unchanged = observer.get(Meter, meter_id)
+        assert unchanged is not None
+        assert unchanged.label == "Original"
+        assert unchanged.note == "Original note"
+
+
 # ---------------------------------------------------------------------------
 # Fixtures
 # ---------------------------------------------------------------------------
@@ -112,6 +171,28 @@ def _make_meter(
     return m
 
 
+def _make_binding(session: Session, meter: Meter, *, started_at: datetime, ended_at: datetime | None = None):
+    source = MeterSource(
+        name=f"source-{meter.id}", kind="dsmr_mqtt", enabled=True, config={}, status="online",
+        created_at=started_at, updated_at=started_at,
+    )
+    session.add(source)
+    session.flush()
+    channel = MeterSourceChannel(
+        source_id=source.id, channel_key=f"channel-{meter.id}", label="Total", unit="kWh",
+        created_at=started_at, updated_at=started_at,
+    )
+    session.add(channel)
+    session.flush()
+    binding = MeterSourceBinding(
+        meter_id=meter.id, channel_id=channel.id, started_at=started_at, ended_at=ended_at,
+        created_at=started_at, updated_at=started_at,
+    )
+    session.add(binding)
+    session.flush()
+    return binding
+
+
 # ---------------------------------------------------------------------------
 # 1. meter_at — half-open interval semantics
 # ---------------------------------------------------------------------------
@@ -637,3 +718,36 @@ class TestUpdateMeter:
         from app.services.meters import _as_utc
         fetched = session.get(Meter, m.id)
         assert _as_utc(fetched.started_at) == _as_utc(earlier)
+
+    @pytest.mark.parametrize("shift", ["later", "earlier"])
+    def test_update_started_at_rejects_boundary_shift_that_strands_binding(self, session: Session, shift: str):
+        """A correction must not create an out-of-epoch binding on either adjacent meter."""
+        boundary = _T0 + timedelta(days=10)
+        prev = _make_meter(session, started_at=_T0, ended_at=boundary, label="Prev")
+        current = _make_meter(session, started_at=boundary, ended_at=None, label="Current")
+        if shift == "later":
+            binding = _make_binding(session, current, started_at=boundary)
+            proposed = boundary + timedelta(days=1)
+        else:
+            binding = _make_binding(session, prev, started_at=_T0, ended_at=boundary)
+            proposed = boundary - timedelta(days=1)
+        session.commit()
+
+        prev_id = prev.id
+        current_id = current.id
+        binding_id = binding.id
+        binding_started_at = binding.started_at
+        binding_ended_at = binding.ended_at
+        with pytest.raises(MeterIntervalError, match="Binding"):
+            update_meter(session, current, started_at=proposed)
+        session.rollback()
+
+        with Session(session.bind) as observer:
+            assert _as_utc(observer.get(Meter, prev_id).ended_at) == boundary
+            assert _as_utc(observer.get(Meter, current_id).started_at) == boundary
+            observed_binding = observer.get(MeterSourceBinding, binding_id)
+            assert observed_binding is not None
+            assert _as_utc(observed_binding.started_at) == _as_utc(binding_started_at)
+            assert (
+                _as_utc(observed_binding.ended_at) if observed_binding.ended_at is not None else None
+            ) == (_as_utc(binding_ended_at) if binding_ended_at is not None else None)